Comparison of P, As & Sb doped Polycrystalline CdTe Solar Cells

Copper-free polycrystalline CdTe solar cells doped with either Phosphorus, Arsenic or Antimony are compared for dopability, device performance and defect properties. In-situ doping of CdTe with group-V elements was carried out using vapor transport deposition followed by CdCl2 heat treatment. Uniform carrier concentration in ~10 ¹⁶ cm ^-3 range is achieved for all three dopants. Compatibility with CdSeTe ternary alloy is demonstrated and comparable quantum efficiency for all three dopants suggests that either dopant could serve as a replacement for copper. These results are compared with previously reported carrier concentration values for group-V doping of sx- and px- CdTe. Theoretical calculation for maximum carrier concentration based on acceptor energy level suggests least ionization of Antimony. Compensation worsens the achievable majority carrier concentration despite high acceptor doping.